Long ago, when the snows still lay heavy on Iowa, an enthusiastic world hymned the wonders of American democracy. See the young people, eyes shining, turning out in their hundreds of thousands. Hear the cheers for candidates - a black man, a woman - that signal profound change. Why can't we (we Brits, say) have a system like that? Why are we stuck with boring old political business as usual?

But now it's summer in Iowa, and what felt inspiring five months ago seems merely interminable. The lady and the black man are still slugging away, exhausting themselves and their funds, staggering with fatigue. What ought to have been an easy, triumphant year for the Democrats has turned into an infernal grind. But this is America, so nobody talks about the "system"; nobody says how crazily self-defeating it is. And, for apostles of proportional representation as universal panacea, PR makes the pantomime season worse.

Who would want, clinically, to describe the way Americans elect their president, a process stuffed full of cash, wasted time, pork barrels and rubber chicken dinners? But - forgetting the fag-end charade of electoral colleges - it is still first past the post. Each state is a constituency with clout geared (roughly) to population, and you win simply by polling more votes - or non-hanging chads - than your opponent. The outcome is a test of crude, not nuanced, strength. So why on earth must the Democrats try to make their primary preliminaries nuanced and "fair"?

There's nothing fair about a mish-mash of caucuses, closed primaries in which only party members can vote, and open ones, where anybody can play. There's nothing fair about a schedule that gives supposedly influential minnows a mighty prominence, and relegates big players to the boondocks of insignificance. There's nothing fair about creating hundreds of spare parts called "superdelegates", then insisting they endorse the candidate who won most non-super backers out in the sticks. Chaos, in short, is never fair.

At least the Republicans, not so keen on tinkering, run their affairs slightly less chaotically: at least John McCain was first past the post two months ago, and able to put his feet up and think.

Let's face it, in New Labour Britain as well as the US, we liberal engineers like complex plans and detailed reforms. If Gordon can adjust the tax system so that only he understands it, then we'll duck and weave and fiddle indefinitely. Three - and possibly four - different voting methods in Scotland? Certainly, sir. A leadership election routine that basically means Labour can't change platforms after Crewe.

But complexity breeds complexity; and in this case, it has bred a primary race so over-extended, so enervating, so grinding, that nobody except journalists with a limitless expense account can call themselves winners. Worse, the divisive manner of "victory" here bears scant relationship to what's needed to carry the country in November.

The pantomime metaphor fits because this is indeed a pantomime horse, wrestling and pulling head against commonsense tail in the dark. It could be fixed easily enough. Hold just one giant primary in March so that Democrats speaking for all America can say who they want to carry their banner - or maybe run four huge regional primaries through a month. But don't pretend that what we see now is too perfect to change. Put all states together on that one day, abolish superdelegates and feed their votes into the general maw, and who would be carrying the banner for the autumn? Probably Clinton, as it happens; just as she'd be the victor now - since Pennsylvania - if first past the post was in operation.

Does that mean she'd be the best candidate? No comment. That's what the voters have been trying to decide for years. But either candidate would be vastly better with a few nights' sleep and a few less speeches deriding other Democrats. And, if McCain wins and doesn't stand again at 76, as he himself hints? Then the race will barely pause for breath before panting ludicrously off on another circuit.

Why doesn't Clinton quit, ask the columnists now. They want their summer holidays, too. But this nightmare of a system isn't designed for easy resolutions as it strives to be "fair". Fairness is sometimes the friend of good governance. But fairness can also - viewed with incredulity from afar - be a fool. It's exciting, sure enough, like the latest Indiana Jones movie, if you like constant pulsating drama: but deep down, when there's governing to be done, it's just stupid.